Cooling air profiling structures for a gas turbine

ABSTRACT

A gas turbine power plant having a combustion chamber including a transition portion to direct hot motive gases to the turbine rotor blades. An array of temperature profiling structures radially project into the transition portion to provide cooling fluid to profile the temperature of the hot motive gases. Each structure comprises a tubular support member having longitudinally extending slits for expansion purposes, the member projecting into an aperture in the transition portion and secured thereto. An air supply conduit is disposed within the support member and is fastened thereto outside of the combustion chamber. The profiling structures are securely positioned but allow for thermal expansion due to the relative temperature differentials among the transition portion, the support member, and the air conduit.

llulted States Patent [191 Arlington et al.

[ COOLING AIR PROFILING STRUCTURES FOR A GAS TURBINE [75] Inventors: Sterling F. Arlington, Philadelphia,

Pa.; Thomas J. Rahaim, Claymont, Del.

[52] 11.8. CI 415/117, 415/175, 60/3966 [51] Int. Cl. F0111 25/12 [58] Field of Search 415/117, 178, 180,

[56] References Cited UNITED STATES PATENTS 1/1970 DeCorso et al 415/117 7/1971 Penny 60/39.65

[111 3,74Lfi7fi June 26, 1973 Primary Examiner--Henry F. Raduazo Attorney-A. T. Stratton, F. P. Lyle and F. Cristiano, Jr.

[57] ABSTRACT A gas turbine power plant having a combustion chamber including a transition portion to direct hot motive gases to the turbine rotor blades. An array of temperature profiling structures radially project into the transition portion to provide cooling fluid to profile the temperature of the hot motive gases. Each structure comprises a tubular support member having longitudinally extending slits for expansion purposes, the member projecting into an aperture in the transition portion and secured thereto. An air supply conduit is disposed within the support member and is fastened thereto outside of the combustion chamber. The profiling struc tures are securely positioned but allow for thermal expansion due to the relative temperature differentials among the transition portion, the support member, and the air conduit.

4 Claims, 3 Drawing Figures COOLING AIR PROFILING STRUCTURES FOR A GAS TURBINE BACKGROUND OF THE INVENTION In gas turbine power plants, it is well known that the higher the operating temperatures are, the higher the thermal efficiency of the power plant. However, it is also well known that the higher the temperature, the more thermal stress to which the blades are subjected. Furthermore, the rotatable blades are subjected to a tensile stress in the radial direction due to the centrifugal force, with the stress being greatest near the root or hub portions of the blades attached to the turbine rotor. Therefore, more recently in gas turbine designs, the temperature of the working fluid is profiled by introducing cooling fluid into the transition portion of the combustion chamber, before contacting the radially inner portions or root portions of the turbine rotor blades, where the stresses are the greatest. This moderates the temperature of the fluid to produce a working fluid temperature profile having decreasing temperature values in an inward radial direction. This, in turn, permits a higher temperature working fluid to be employed against the radially outer portions of the blades, where the stresses are not as great so that more energy can be extracted toward the tips of the blades and v thereby increasing turbine efficiency.

One such turbine profiling structure is shown and described in S. M. DeCorso and C. E. Carlson US. Pat. No. 3,490,747 patented Jan. 20, 1970, and assigned to the present assignee. In this structure, a plurality of tubular shaped noz'zle structures are secured to an annular support structure disposed adjacent the downstream portion of the transition member and are in fluid communication with the compressor section of the power plant through an annular passageway. Cooling air from the compressor flows through the axial passageway into a chamber defined by the support structure and, because of the pressure differential, flows into the path of the hot combustion gases to profile the temperature thereof before contacting the turbine rotor blades. This type of profiling structure has commerically proven operable but problems have been encountered. The annular support structure is a separate and independent element of the power plant which is relatively expensive to manufacture and install, because it is a relatively heavy structure since it must support the air profiling structures, it must withstand the forces from the pressurized cooling fluid therein, and it must also withstand the high temperature differentials to which it is exposed, i.e. at one end it is exposed to the hot combustion gases, and at the other end, it is exposed to the compressor cooling air. In operation, the support structures have warped, thereby creating problems associated with maintaining the proper positioning of the profiling structures.

Another proposed solution is disclosed in J. A. Laurelli and R. S. Adelizzi copending application Ser. No. 103,331, filed Jan. 14, 1971, now abandoned and assigned to the present assignee. The profiling structure there disclosed is an annular segmented support structure having radially extending cooling tubes projecting into slots in the transition member. However, this profiling structure is also subjected to warping since no provisions are made for providing for the temperature differentials among the cooling tubes, the transition member, and the support structure. Furthermore, the

support structure is also a separate element which must be constructed and inserted into the power plant at additional cost and requires relatively close tolerances.

What is desired then, is temperature profiling means for supplying cooling air to the flow path of hot combustion products, which profiling means would eliminate the heavy annular supporting structures presently used for supporting and retaining the cooling air conduits in place, and furthermore, provide means for allowing thermal expansion among the transition member, the supporting structure, and the air supply conduit to allow for increased reliability of the profiling means.

SUMMARY OF THE INVENTION The following relates to a gas turbine power plant and more specifically to apparatus for profiling the temperature of hot combustion products flowing to the turbine.

An annular array of profiling temperature structures radially project into a transition portion of a combustion chamber to provide cooling fluid from the compressor to profile the temperature of the hot motive gases.

In accordance with the invention, each profile structure is secured directly to the transition portion of the combustion chamber and comprises a tubular support member having longitudinal slits extending to one end of the support member. That end of the support member projects into a corresponding aperture in the transition portion and is secured thereto. An air supply conduit is disposed concentrically within the support member and is fastened thereto at the opposite end, outside of the combustion chamber.

The slits in the support member allow the member to expand and contract relative to thermal conditions and the member also firmly maintains the air conduit in proper position. The annular support structures shown and described in the above cited patent and copending application are eliminated and a more economical and reliable temperature profiling structure results.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a view showing a partial longitudinal section of an axial flow gas turbine having temperature profiling structures formed in accordance with this invention;

FIG. 2 is a view taken along line IIII in FIG. I; and

FIG. 3 is an enlarged isometric view of the profiling structure shown in FIG. 1.

DESCRIPTION OF THE PREFERRED EMBODIMENTS Referring to the drawings in detail, and particularly to FIG. 1, there is shown a portion of an axial flow gas turbine 10. The turbine 10 comprises an outer casing 11 of generally tubular shape, an inner casing 12 of tubular shape encompassed by the outer casing 11 and a rotor structure 13 rotatably supported within the inner casing 12 in any suitable manner (not shown). At least one annular row of rotating blades 16 (only one row being shown) extend radially outward from the rotor structure 13. Cooperatively associated with the rotating blades to form a stage for motive fluid expansion is at least one annular row of stationary blades 14 (only one row being shown) which are supported within the inner casing 12. The first stationary row of blades 14 and the first rotating row 16 is defined as the first stage 17.

Hot motive fluid, such as pressurized combustion gas is generated in a plurality of circumferentially disposed combustion chambers 25, (only one being shown). The chambers 25 are of the well known canister type having cylindrical portions at the upstream end 26 and transition duct portions 27 at the downstream end 28. The transition duct portions 27 change in cross sectional shape from circular cross section at the jointure with the cylindrical portion to generally arcuate cross section at the outlet 29 (FIGS. 1 and 2). The outlets 29 are in a closely spaced annular relation and jointly form an annular outlet to direct the hot motive gases to the first stage 17 of the turbine in a full and continuous peripheral stream. The gases flow past the stationary blades 14 and the rotary blades with resulting expansion of the gases to rotate the rotor structure 13 about its rotational axis R-R.

As seen in FIG. 1, the combustion chambers 25 are disposed within the outer casing 11 in a plenum chamber 31 which is pressurized by air from a compressor (not shown). The pressurized air is directed into the combustion chambers 25 to mix with the fuel to form a combustible mixture which is burned to provide the hot motive gases. A sealing structure generally designated 33 is provided at the downstream end 28 of the transition portion 27, between each pair of adjacent transition portions, to partially define the plenum chamber 31 and to prevent pressurized air from leading into the turbine stages. The sealing structure 33 may preferably be of the type described and shown in copending application by G. M. Mierley and T. J. Rahaim, application Ser. No. 32,926, filed Apr. 29, 1970 now US Pat. No. 3,609,968.

In accordance with the principles of this invention, there is provided an annular array of temperature profiling structures 35 radially projecting into the transition portion 27 of the combustion chamber 25. The profiling structures 35 are located at the downstream end 28 of the transition member 27 and upstream of the outlets 29, and are disposed on the radially inner side of the member 27 (FIGS. 1 and 2) relative to the rotational axis R-R of the turbine.

Since the profiling structures 35 are substantially identical to each other, only one will be described. As best seen in FIG. 3, the profiling structure 35 is comprised of two members. The first is a tubular support member or sleeve 37 and the second is a cooling fluid supply member or conduit 39.

The sleeve 37 has a larger diameter than the corresponding conduit 39 and the conduit 39 is telescopically disposed within the sleeve. A plurality of slits 41 extend longitudinally on the body of the sleeve 37. The slits 41 extend from a set longitudinal distance from one end 43 (the radially inner end) of the sleeve 37 to the outer end 44 (the radially outer end) and cut the end 44. The slits 44 define a corresponding number of longitudinally extending fingers 46. The fingers 46 provide the needed flexibility to allow for thermal expansions and contractions.

The conduit 39 is disposed within the larger sleeve 37 and is longer than the sleeve so that one end (the radially outer end) projects substantially beyond the sleeve. The conduit 39 is secured at the radially inner end 43 of the sleeve by any suitable means such as by welding 40. The radially outer end of the conduit 39 is not fastened to the radially outer end 44 of the sleeve 37 but is supported thereby.

A plurality of apertures 48 are on the radially inner wall member of each transition portion 27, one aperture 48 corresponding to each profiling structure 35. Each profiling structure 35 is inserted radially relative to the rotational axis of the turbine 10 into the corre sponding aperture 48 and into engagement with the transition portion 27. The radially outer end 44 of the sleeve 37 is firmly fastened to the transition member 27 by any suitable means such as by welding, and as shown in FIGS. 2 and 3, is welded on the inner and outer surfaces 50 and 51 respectively, of the radially inner portion of the transition member 27.

In operation, combustion gases are generated in the combustion chambers 25 and are directed by the transition portions 27 to the turbine rotor structure 13. Air from the compressor (not shown) pressurizes the plenum chamber 31 and because of the pressure differential between the plenum chamber and the combustion chamber, pressurized cooling air is forced through the temperature profiling structures 45 to profile the hot combustion gases before they reach the turbine blades 14, and 16 to provide a more effective extraction of en ergy, as previously explained.

During the initial turbine start up period, the conduit 39 extending radially into the hot gaseous flow path heats up more quickly than the wall of the combustion chamber 25. Therefore, during this transient condition, the conduit 39 thermally expands more rapidly than the transition member 27. In the circumferential direction, conduit 39 grows larger. The fingers 46 of the support member 37 can expand circumferentially because of the slits 41 and therefore the energy due to the circumferential expansion of the conduit 39 is substantially transferred to the support structure 37 and dissipated. The structure 37 therefore exerts no thermal stress on the welds 50 and 51 and no rupturing of the welds 50 and 51 occurs.

In the normal operating condition, or the stable condition, the transition portion 27 is substantially hotter than the temperature profiling structure 35, since the relatively cool air is flowing through the supply conduit 39, convectively cooling it (FIG. 3). Therefore, the transition member has greater thermal expansion than the respective conduit 39. Since the support structure or sleeve 37 is welded to the transition member 27, it expands circumferentially therewith, due to the flexibility in the fingers 46, thereby leaving a small annular gap between the conduit 39 and the support member 37 at the radially outer end 44. However, the conduit 39 is secured to the support member 37 at the radially inner end 43 thereof, which is outside of the combustion chamber 26 at a sufficient radial distance so that the radially inner end of both the conduit and the support structure are substantially at the same temperature. The support member 37 expands longitudinally in a radially inner direction and conduit 39 expands longitudinally in a radially outer direction so that neither member 37 nor conduit 39 is subject to thermal stress. Therefore, there is no thermal stress on the weld 40 at the radially inner end of the profiling structure 35 and furthermore, the structure is still properly maintained in its profiling position relative to the combustion chamber 25, since the longitudinal expansion of the support member 37 substantially cancels the opposite expansion of the conduit 39.

These profiling structures 35 provide substantial advantages over present profiling structures wherein rela- Though the invention has been described with a certain degree of particularity, modifications are possible without departing from the spirit and scope of the invention. For example, the profiling structures 35 may be inserted to extend to various radial heights and may be inclined at various angles relative to the combustion chamber 25. Furthermore, although the profiling structures 35 are shown inserted in the radially inner wall of the transition member 27 at the downstream end 28 thereof, the invention is not limited thereto.

1 claim as my invention: 1. In a gas turbine power plant, having a bladed rotor portion and a combustion chamber where hot products of combustion are formed and directed to the rotor portion to motivate the same, at least one temperature profiling structure for directing cooling fluid into the path of the combustion products, said profiling structure comprising:

a cooling fluid conduit;

means for supporting said conduit relative to said combustion chamber;

said profiling structure extending into said combustion chamber;

means providing for relative thermal expansion among said combustion chamber, said supporting member, and said conduit;

said supporting means secured to said conduit and said combustion chamber and comprising a tubular sleeve member encompassing the cooling fluid conduit;

and said expansion means comprising a plurality of longitudinally extending slits along the sleeve memher;

said slits defining a plurality of longitudinally extending fingers;

said fingers being flexible to allow for relative thermal expansion.

2. In a gas turbine power plant, having a bladed rotor portion and a combustion chamber where hot products of combustion are formed and directed to the rotor portion to motivate the same, at least one temperature said combustion chamber;

said profiling structure extending radially into said combustion chamber;

means providing for relative thermal expansion among said combustion chamber, said supporting member, and said conduit;

the support means comprising a tubular support member encompassing the cooling fluid conduit;

the radially inner end of said support member being secured to the radially inner end of the conduit;

the expansion means including a plurality of slots extending longitudinally along the support member and disposed in a radial direction;

said slots extending to the radially outer end of said support member;

said slots thereby defining a plurality of longitudinally extending flexible finger structures;

and said radially outer end of said support member being secured to the inner wall of the combustion chamber.

3. In an axial flow elastic fluid utilizing machine, said machine having a turbine portion and a combustion portion, said combustion'portion having an outer wall structure partially defining a pressurized plenum cham ber, an annular array of combustion chambers equally spaced from each other and from the rotational axis of the machine disposed within said plenum chamber, said combustion chambers each having a transition portion defining a flow path to supply hot products of combustion to said turbine portion, a plurality of temperature profiling structures for directing cooling fluid from within said plenum chamber into the path of the combustion products within the transition portion, said profiling structure comprising:

a tubular cooling fluid conduit radially extending into an inner wall of said transition member;

a large diameter tubular sleeve member encompassing said conduit for support thereof,

said conduit and sleeve member being fastened together at their radially inner ends,

the radially outer end of said sleeve member being securely fastened to the inner wall of the transition member,

each of said sleeve members being free to expand in a radially inward direction and each of said conduit members being free to expand in a radially outer direction so that the expansions tend to negate each other resulting in said profiling structures remaining substantially in the same radial positions.

4. The structure recited in claim 3 wherein:

a plurality of longitudinally slots extending along the sleeve member to the radially outer end of said sleeve member,

said slots thereby defining a plurality of flexible finger structures,

said finger structures providing for relative thermal expansion among said transition portion, said sleeve member, and said cooling fluid conduit in a circumferential direction. 

1. In a gas turbine power plant, having a bladed rotor portion and a combustion chamber where hot products of combustion are formed and directed to the rotor portion to motivate the same, at least one temperature profiling structure for directing cooling fluid into the path of the combustion products, said profiling structure comprising: a cooling fluid conduit; means for supporting said conduit relative to said combustion chamber; said profiling structure extending into said combustion chamber; means providing for relative thermal expansion among said combustion chamber, said supporting member, and said conduit; said supporting means secured to said conduit and said combustion chamber and comprising a tubular sleeve member encompassing the cooling fluid conduit; and said expansion means comprising a plurality of longitudinally extending slits along the sleeve member; said slits defining a plurality of longitudinally extending fingers; said fingers being flexible to allow for relative thermal expansion.
 2. In a gas turbine power plant, having a bladed rotor portion and a combustion chamber where hot products of combustion are formed and directed to the rotor portion to motivate the same, at least one temperature profiling structure for directing cooling fluid into the path of the combustion products, said profiling structure comprising: a cooling fluid conduit; means for supporting said conduit relative to said combustion chamber; said supporting means secured to said conduit and said combustion chamber; said profiling structure extending radially into said combustion chamber; means providing for relative thermal expansion among said combustion chamber, said supporting member, and said conduit; the support means comprising a tubular support member encompassing the cooling fluid conduit; the radially inner end of said support member being secured to the radially inner end of the conduit; the expansion means including a plurality of slots extending longitudinally along the support member and disposed in a radial direction; said slots extending to the radially outer end of said support member; said slots thereby defining a plurality of longitudinally extending flexible finger structures; and said radially outer end of said support member being secured to the inner wall of the combustion chamber.
 3. In an axial flow elastic fluid utilizing machine, said machine having a turbine portion and a combustion portion, said combustion portion having an outer wall structure partially defining a pressurized plenum chamber, an annular array of combustion chambers equally spaced from each other and from the rotational axis of the machine disposed within said plenum chamber, said combustion chambers each having a transition portion defining a flow path to supply hot products of combustion to said turbine portion, a plurality of temperature profiling structures for directing cooling fluid from within said plenum chamber into the path of the combustion products within the transition portion, said profiling structure comprising: a tubular cooling fluid conduit radially extending into an inner wall of said transition member; a large diameter tubular sleeve member encompassing said conduit for support thereof, said conduit and sleeve member being fastened together at their radially inner ends, the radially outer end of said sleeve member being securely fastened to the inner wall of the transition member, each of said sleeve members being free to expand in a radially inward direction and each of said conduit members being free to expand in a radially outer direction so that the expansions tend to negate each other resulting in said profiling structures remaining substantially in the same radial positions.
 4. The structure recited in claim 3 wherein: a plurality of longitudinally slots extending along the sleeve member to the radially outer end of said sleeve member, said slots thereby defining a plurality of flexible finger structures, said finger structures providing for relative thermal expansion among said transition portion, said sleeve member, and said cooling fluid conduit in a circumferential direction. 